A Good Reason to Jump on the Bed

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

A Good Reason to Jump on the Bed

Dominoes, those thin toy rectangles with dots on them, can make really cool domino chains. You stand up a whole lot of dominoes in a row, so when one tips over, it knocks down the next domino, which knocks down the next, making a long rippling wave across the room. Someone decided to try a chain of super-huge dominoes — using real people holding onto bed mattresses! As we see in this video, a couple of years ago 850 people in New Orleans tried to break the world record for the longest human domino chain. They all worked for the hotel company La Quinta Inns, and the mattresses were given to the event by Simmons. Every single person fell over as planned. Best of all, when they were all done they got to jump up and down on their mattresses.

Wee ones: Who’s taller, the mattresses or the people holding onto them?

Little kids: If part of the mattress chain starts with a man, then a woman on the next one, then a man, then a woman…who’s the 8th mattress tipper? Bonus: Who’s the 20th?

Big kids: If every 3rd person yells while tipping over (starting with the 3rd participant), who’s the 7th tipper to yell? Bonus: If it took 1 second for each mattress to tip over, would the whole 850-person chain finish in 10 minutes? (Reminder if needed: A minute has 60 seconds.)

The sky’s the limit: If the people line up in equal-length rows, and the number of people in each row ends in a zero, how many ways can they line up in rows — and with how many people in each? (Assume there’s more than 1 long 850-person row.)

Answers:Wee ones: The mattresses are taller.

Little kids: A woman since even numbers are women. Bonus: Also a woman.

Big kids: The 21st tipper. Bonus: No, because 10 minutes would be enough time for only 600 mattresses to fall (60 x 10).

The sky’s the limit: There are 3 ways to line up. This is a factoring problem: 850 = 10 x 85 = 5 x 2 x 5 x 17. So the only numbers ending in 0 that divide into 850 are 10 (5 x 2), 50 (5 x 2 x 5), and 170 (5 x 2 x 17). Thus we have 85 rows with 10 people in each, 17 rows with 50 people in each, or 5 rows with 170 in each!

About the Author

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.